At present, many home appliances are available which can be remotely controlled by the user. For example, a television set can be turned on and off, a channel can be selected, a video cassette recorder controlled to play or record, etc. However, each manufacturer effects this control differently. The bit pattern required to carry out a given operation differs for different manufacturers. Similarly, the basic format, such as the bit timing, the number of bits per word, the width of the pulses, the modulating frequency, if any, applied to each pulse, the presence of, length of, and format of start, lead, or trailer pulses and the number of correct receptions of a particular command required to activate the appliance to carry out the selected operation varies from manufacturer to manufacturer. The basic format may also be different for different model numbers of the same manufacturer.
Further, control of, for example, a video cassette recorder frequently requires the ability to control a related appliance, e.g. a television set, in conjunction therewith. At present, viewing a recorded program requires use of two individual remote control units, particularly if the recorder and the television set are not made by the same manufacturer. If the home is equipped with cable television, or if other appliances such as, for example, an oven can be remotely controlled, the number of required remote control transmitters becomes excessive. In addition, each time the user replaces an appliance the old remote control unit becomes obsolete and a new one must be bought.